INT-3926: Add <poller> for all outbound tags

JIRA: https://jira.spring.io/browse/INT-3926

* Add `<poller>` for all `<outbound-adapter(gateway)>`
* Add/modify tests for `<queue>` as an input channel and particular `<poller>`
* Move XSD from the `xml` package to the `config` level to achieve the consistency throughout the project.

spring-integration-jdbc/src/main/resources/org/springframework/integration/jdbc/config/spring-integration-jdbc-4.3.xsd

@@ -721,6 +721,7 @@
 		<xsd:complexType>
 			<xsd:sequence>
 				<xsd:sequence>
+					<xsd:element ref="integration:poller" minOccurs="0" maxOccurs="1" />
 					<xsd:element name="sql-parameter-definition" minOccurs="0"
 							maxOccurs="unbounded" type="sqlParameterDefinitionType">
 						<xsd:annotation>